Flowmaster rust through

[JustJCarr73]

Ive heard a lot of complaints about Flowmaster exhaust rusting through aftr a year or two. My question is, if I painted my exhaust and cats with rustoleum, would this be a good preventaive measure? What about headers, should I worry about them rusting through? I want o protect my investment.

JCarr

[beef_bourito]

it depends on how well the rustoleum handles heat. cats and headers are very hot and it might just crust up and fall off, or it might become ineffective. i don't see any problem doing the muffler because it tends not to get nearly as hot, but i'm not sure about headers and cats.

[curtis73]

The first time you ran it, the paint would burn off, or worse possibly catch fire. Rust happens mainly from the inside out. Extreme temps and lots of water from combustion make the rust happen. External salt and corrosion play a role, but the worse factor is inside rust.

If you look at a flaky rusty muffler that has rusted through, chances are the inside is worse at the point where water collected.

[GreyGoose006]

best way to keep your muffler from rusting thru is to not drive it on little short trips all the time.
my mom drives 1.5 miles to work and back every day but never lets her car warm up fully.
as a result she goes thru about 2 mufflers a year.

the reason is that when the hot exhaust pipes cool, water condenses and it collects in the muffler. if the muffler never gets hot enough to burn off the water then it just rusts away.

[win_daddy]

One thing you might check for is a drain hole in the bottom of the muffler, usually near the seam on the low end. I've notice that all factory mufflers have a little drain hole, but often the aftermarket doesn't provide one. If you don't see one, try drilling a 1/8" or smaller hole for water to drain. If you do make a lot of short trips, this will help the muffler last longer. Of course, if you get a stainless steel muffler to begin with, then it's not an issue.... ;-)

[curtis73]

^^^ or at least not as much of an issue. My 304 stainless muffler looks like raisin bran after 98,000 miles.

[GreyGoose006]

but wont drilling a hole defeat the whole purpose of having a muffler?

[2.2 Straight six]

Originally Posted by GreyGoose006

but wont drilling a hole defeat the whole purpose of having a muffler?

it's not a big enough hole to make much of a difference.

[JustJCarr73]

Im sure glad i asked then because I never would of thought to drill a hole through the muffler. And I iniially asked this question because I saw rust-o-leum has a high temperture vaariety that is marketed to paint your engineblock with, thats what gve me the idea of protectign my pipes with it.

Thanks again guys

JCarr

[JustJCarr73]

Where on the muffler should I drill this drainage hole? I have the flowmaster 70 series single inlet dual outlet